Method and means for emitting sig



Oct. 22, 1940. v PARSBERG 2,219,019

umaon AND MEANS FOR EMITTING SIGNALS WITH vmnue smrm. CHARACTER OriginalFiled Dec. 22, 19:2

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WITNESS I W flTTGRN) Patented Oct. 22, 1940 UNITED STATES PATENT OFFICEMETHOD AND MEANS FOR EMITTING SIG- NALS WITH VARYING ACTER SIGNAL CHAR-Jersey Original application December 22, 1932, Serial No.

Divided and this application Septem-- ber 30, 1937, Serial No. 166,538.In Sweden December 24, 1931 8 Claims.

Application was. filed in Sweden December 24, 1931, and in the UnitedStates December 22, 1932, Serial No. 648,348. The present application isa division of United States application Serial No. 648,348, on whichPatent No. 2,096,755 issued October 26, 1937.

It has become the general practice in arranging the illumination of airroutes to use powerful revolving searchlights projecting beams ofcondensed light which sweep the horizon. When these beams of light sweeppast a certain point, the impression obtained in the said point is thatof a flashlight character, usually single flash. The period between theseparate flashes varies in length in different countries. In America,for instance, it is considered suflicient with one flash every tenseconds, whereas in Germany they have generally gone in for a period ofabout three seconds. If it is taken into consideration that it has beenthe practice for years to provide one flash every five seconds formarine traffic, which moves much slower, the conclusion is easilyarrived at that for aviation the period should be quicker and notslower, and consequently that a period of three seconds would be more inaccordance with the requirements of air traflic.

Flashes at shorter intervals may be obtained by increasing the rotaryspeed of the apparatus or by dividing the available light energy intoseveral beams. In both cases the efficiency of the beacon will bereduced. In the first case the light impression will be diminished,owing to the reduced duration of the flash (according to the Blondel andRey law), while in the latter case the light efficiency of the beaconwill be reduced by the division of the light energy.

The Frenchmen Blondel and Rey have scientifically proved that, in orderto obtain a flashlight of a light range equivalent to that of fixedlight, the light power of the flashlight must be larger andconsequently, in order to express its equivalent in terms of a fixedlight, the light power of a flashlight must be multiplied by a factorwhich is less than 1. This factor is dependent on the duration of theflash and diminishes quickly as this is reduced. The factor in questionis, for instance, approximately .2 for a flash of .03 second, .48 for aflash of .1 second, and rises to .84 for a flash of .3 second.

From this point of View, it would be advantageous in order to obtain agood light impression or a good signal effect, to have a long durationof the flash, which can be attained by increasing the width of the lightbeam or by reducing the rotary speed of the beacon. From the point ofview of light economy the first-mentioned way of solving the question isnot to be recommended. On the other hand, a reduction of the rotaryspeed will mean that the interval between the separate flashes will belonger. As stated above, it is desirable that this interval should becomparatively short.

It is evident that the two requirements which thus present themselves,particularly in the technique of airway beacons, i. e., long duration ofthe flash on the one hand and short intervals between the separateflashes on the other, are at variance with each other, inasmuch ascompliance with one of the requirements requires a low rotary speed,whereas, the other requires high rotary speed of the beacon.

This invention refers to an arrangement by means of which theabove-mentioned features are both attained simultaneously, the lens orreflector system of the beacon being soarranged O as to provide atwo-part beam, one part of which rotates while the other part oscillateswith a revolving motion in such a way that the signal character of thebeam or beams of light will be difierent in diiferent directions.Preferably, according to the invention, the rotating lens or reflectorsystem of the beacon is not allowed to revolve uniformly as has been thepractice hitherto, i. e., withan approximately constant speed in thesame direction, but is instead given a nonuniform revolving motion. Bynon-uniform revolving motion is to be understood in this connection thatin certain sections of the revolution the system revolves at a slowerspeed. than in other sections.

The intention with such a non-uniform revolving motion is to improve thelight impression in certain sections of the revolution at the expense ofthe light impression in the other sections. When the beacon is intendedas an airway beacon, the flying direction is suitably laid through thefirst-mentioned sections because the beacon light should be most visiblein that direction, whereas the other sections donot as a rule requirefull light power.

In one form of employing the invention the rotating lens or reflectorapparatus is, as mentioned above, given a lower angular speed when thebeam or beams of light sweep past the flying two lens panels. arrangedat an angle of 180 between their optical axis, and giving at a constantrevolving speed and a period of, say, five seconds, a flash of aduration of .10 second, thus will be arranged successively to alter therevolving speed. When beams of light from the lens panels pass theflying direction, the speed of the beacon has been reduced to one-third,whereas the speed has been increased three times when the 1 same lightbeams pass directions which are at right angles to the flying direction.Then the light efficiency of the beacon in the flying direction willsuccessively be-increased by about 80%, whereas the light efiiciency indirections which are at right angles to the flying direction willsuccessively be reduced to about half.

Fig. 1 of the drawing is'a diagrammatic illustration of the inventionutilizing two lens or reflector devices, one revolving, and the otheroscillating within an angle of the rotation of the first;

Fig. 2 is a vertical sectional View through the apparatus. for use inpractising the invention;

Fig. 3 is a transverse sectional view taken on the line G-H of Fig. 2;and

Fig. 4 is a similar view taken on the line IK of Fig. 2.

In the present form of employing the invention, two lens or reflectorapparatus are co-operating, one of which revolves, whereas the otherturns back and forth within an angle of any size, as is shown by thecurves e and .2 respectively, Fig. 1. Within the revolving angle to ofthe last mentioned apparatus and outside this angle, respectively,different light characters may be obtained by adjusting the motion ofthe revolving lens apparatus in relation to the oscillating motion, asshown to the left and to the right, respectively, in the diagram. Fromthe diagram to the left is seen that the aviator receives a mixed singleand double flash character furthest out towards starboard, andthree-flash character furthest out towards the port side. Outside therevolving angle w a slow single-flash character is obtained in relationto the character within the said angle. The revolving angle is the limitof the flying route. If the connecting line between two successivebeacons is laid along one of the legs of the revolving angle and the twoopposing flying angles of two such successive beacons are on oppositesides of this connecting line, there can be no collision of aeroplanescoming from op posite directions, provided that the pilots always keepinside the angle to of the beacon in front of them.

In this form of employing the invention, the character of the signalwithin the flying angle to can be very rapid, and alterations in thecharacter are thus easily noticed.

Lights of the description in question make the use of special so-calledcourse lights unnecessary, because the aviator will notice an alterationin the flying character as soon as he deviates from the flying course.

The above-described forms of arranging the light may naturally also beused for maritime beacons, or for maritime and airway beacons combined.

In the arrangement of apparatus shown by Figs. 2, 3 and 4, the lenssystem is divided in two parts, one of which revolves, and the otherturns back and forth within an angle of any size, corresponding to thediagram of Fig. 1. Fig. 2 shows a form of employing the inventionwherein a source of light 5 cooperates with two lens apparatus arrangedone on top of the other, one of them revolving and the otheroscillating. The upper part 74 is supported by the rods 66, which aresecured to a table 6'! revolving around the shaft 65. The lower lenspart 13 rests on the disk 64 placed :on the shaft65. The table 6? andthe upper lens part 14 are caused to revolve at a periodically varyingrevolving speed :by means of the elliptic gear 76, TI driven by theshaft 15. The lower lens part 13, on the other hand, is caused to moveback and forth by means of the cam 18 arranged on the shaft 15 forsooperating with the arm 79, secured on the shaft 65.

It will be apparent from this structure that uniform rotary motionapplied to the shaft I5 will be transformed into non-uniform motion bythe elliptic gears TB, 11, and that the upper lens part 14 will have alower speed when the beam sweeps through the angle forming the flyingdirection. It will also be apparent that the cam 18 in cooperation withthe arm 19 will cause the lower lens part 13 to oscillate within theangle forming the flying direction. The result of the operation of suchan arrangement of lenses is Having thus described my invention, what Iclaim and desire to secure by Letters Patent is:

1. The method of producing signals with different signaling character indifierent directions, comprising the directional emission of two beamsof radiant energy from a source, continuously rotating one of said beamsin a plane around said source at uniform time intervals, and oscillatingthe other beam around said source substantially in the same planethrough a predetermined angle at uniform time intervals.

2. The method of producing signals with different signaling character indiflerent directions, comprising the directional emission of two beamsof radiant energy from a source, continuously rotating one of said beamsin a plane around said source at uniform time intervals andsubstantially decreasing the angular speed of said beam through a.pre-determined angle of its rotation,.and oscillating the other beamaround said source through said angle inv substantially the same plane.

3. The method of producing signals with different signaling character indilferent directions, comprising the emission of two pairs of oppositelydirected beams of radiant energy from a source, continuously rotatingone of said pairs of beams in a plane and around said source at uniformtime intervals, and oscillating the other pair of beams substantially inthe same plane and around said source through pre-determined angles atuniform time intervals.

4. The method of producing signals with different signaling character indifferent directions, comprising the emission of two pairs of oppositelydirected beams of radiant energy from a 2.

source, continuously rotating one of said pairs of beams in a plane atuniform time intervals and substantially decreasing the angular speed ofsaid beams through ore-determined angles of th ir re el io and os at the a beams through said angles in said plane at uniform time intervals.

5. In route signaling apparatus, the combination of a source of radiantenergy, separate projecting means for producing from said energy twobeams independently movable substantially in the same plane, a rotatablesupport for each of said projecting means, mechanism for continuouslyrotating one of said supports to thereby rotate one of said beams insaid plane around said source at uniform time intervals, and mechanismtor continuously oscillating the other support to thereby oscillate theother beam through a pre-determined angle in said plane at uniform timeintervals.

6. In route signaling apparatus, the combination of ;a source of radiantenergy, separate projecting means for producing from said energy twobeams independently movable substantially in the same plane, a rotatablesupport for each of said projecting means, mechanism for continuouslyrotating one of said supports to thereby rotate one of said beams insaid plane around said source at uniform time intervals, means forsubstantially decreasing the rotary speed of said support through apre-determined angle of its movement, and mechanism for continuouslyoscillating the other support to thereby oscillate the other beamthrough said angle in said plane at uniform time intervals.

7. In route signaling apparatus, the combination of a source of radiantenergy, separate projecting means for producing from said energy twobeams independently movable substantially in the same plane, a rotatablesupport for each of said projecting means, a continuously rotatingdriving shaft, motion transmitting means between said driving shaft andone of said supports to rotate said support at uniform time intervalsand with substantially decreased speed through a certain angle of itsmovement, and motion transmitting means between said driving shaft andthe other support to oscillate the latter support within said angle atuniform time intervals.

8. In route signaling apparatus, the combination of a source of radiantenergy, separate projecting means for producing from said energy twobeams independently movable substantially in the same plane, a rotatablesupport for each of said projecting means, a continuously rotatingdriving shaft, apair 'of intermeshing elliptical gears between saiddriving shaft and one of said supports to rotate said support withsubstantially decreased speed through a certain angle of its movement, acam arm on the other of said supports, and a cam on said driving shaftfor cooperating with said cam arm to oscillate the latter support withinsaid angle at uniform time intervals.

ERIK ROBERT PARSBERG.

